1,025 research outputs found
Experimental high-intensity three-photon entangled source
We experimentally realize a high-intensity three-photon
Greenberger-Horne-Zeilinger (GHZ) entanglement source directly following the
proposal by Rarity and Tapster [J. G. Rarity and P. R. Tapster, Phys. Rev. A
59, R35 (1999)]. The threefold coincidence rate can be more than 200 Hz with a
fidelity of 0.811, and the intensity can be further improved with moderate
fidelity degradation. The GHZ entanglement is characterized by testing the
Bell-Mermin inequality and using an entanglement witness operator. To optimize
the polarization-entangled source, we theoretically analyze the relationship
between the mean photon number of the single-photon source and the probability
of parametric down-conversion.Comment: 4 pages, 4 figure
How effectively does metamorphic testing alleviate the oracle problem?
In software testing, something which can verify the correctness of test case execution results is called an oracle. The oracle problem occurs when either an oracle does not exist, or exists but is too expensive to be used. Metamorphic testing is a testing approach which uses metamorphic relations, properties of the software under test represented in the form of relations among inputs and outputs of multiple executions, to help verify the correctness of a program. This paper presents new empirical evidence to support this approach, which has been used to alleviate the oracle problem in various applications and to enhance several software analysis and testing techniques. It has been observed that identification of a sufficient number of appropriate metamorphic relations for testing, even by inexperienced testers, was possible with a very small amount of training. Furthermore, the cost-effectiveness of the approach could be enhanced through the use of more diverse metamorphic relations. The empirical studies presented in this paper clearly show that a small number of diverse metamorphic relations, even those identified in an ad hoc manner, had a similar fault-detection capability to a test oracle, and could thus effectively help alleviate the oracle problem
Understanding the Clean Interface between Covalent Si and Ionic Al2O3
The atomic and electronic structures of the (001)-Si/(001)-gamma-Al2O3
heterointerface are investigated by first principles total energy calculations
combined with a newly developed "modified basin-hopping" method. It is found
that all interface Si atoms are fourfold coordinated due to the formation of
Si-O and unexpected covalent Si-Al bonds in the new abrupt interface model. And
the interface has perfect electronic properties in that the unpassivated
interface has a large LDA band gap and no gap levels. These results show that
it is possible to have clean semiconductor-oxide interfaces
The mechanism of the polarization dependence of the optical transmission in subwavelength metal hole arrays
We investigate the mechanism of extraordinary optical transmission in
subwave-length metal hole arrays. Experimental results for the arrays
consisting of square or rectangle holes are well explained about the dependence
of transmission strength on the polarization direction of the incident light.
This polarization dependence occurs in each single-hole. For a hole array,
there is in addition an interplay between the adjacent holes which is caused by
the transverse magnetic field of surface plasmon polariton on the metal film
surfaces. Based on the detailed study of a single-hole and two-hole structures,
a simple method to calculate the total tranmissivity of hole arrays is
proposed.Comment: 34 pages, 7 figure
Method of determining cosmological parameter ranges with samples of candles with an intrinsic distribution
In this paper, the effect of the intrinsic distribution of cosmological
candles is investigated. We find that, in the case of a narrow distribution,
the deviation of the observed modulus of sources from the expected central
value could be estimated within a ceratin range. We thus introduce a lower and
upper limits of , and , to
estimate cosmological parameters by applying the conventional minimizing method. We apply this method to a gamma-ray burst (GRB) sample as well as
to a combined sample including this GRB sample and an SN Ia sample. Our
analysis shows that: a) in the case of assuming an intrinsic distribution of
candles of the GRB sample, the effect of the distribution is obvious and should
not be neglected; b) taking into account this effect would lead to a poorer
constraint of the cosmological parameter ranges. The analysis suggests that in
the attempt of constraining the cosmological model with current GRB samples,
the results tend to be worse than what previously thought if the mentioned
intrinsic distribution does exist.Comment: 6 pages,4 figures,1 tables.Data updated. Main conclusion unchange
Experimental Long-Distance Decoy-State Quantum Key Distribution Based On Polarization Encoding
We demonstrate the decoy-state quantum key distribution (QKD) with one-way
quantum communication in polarization space over 102km. Further, we simplify
the experimental setup and use only one detector to implement the one-way
decoy-state QKD over 75km, with the advantage to overcome the security
loopholes due to the efficiency mismatch of detectors. Our experimental
implementation can really offer the unconditionally secure final keys. We use 3
different intensities of 0, 0.2 and 0.6 for the pulses of source in our
experiment. In order to eliminate the influences of polarization mode
dispersion in the long-distance single-mode optical fiber, an automatic
polarization compensation system is utilized to implement the active
compensation.Comment: 4 pages,3 figure
Electric fields and valence band offsets at strained [111] heterojunctions
[111] ordered common atom strained layer superlattices (in particular the
common anion GaSb/InSb system and the common cation InAs/InSb system) are
investigated using the ab initio full potential linearized augmented plane wave
(FLAPW) method. We have focused our attention on the potential line-up at the
two sides of the homopolar isovalent heterojunctions considered, and in
particular on its dependence on the strain conditions and on the strain induced
electric fields. We propose a procedure to locate the interface plane where the
band alignment could be evaluated; furthermore, we suggest that the
polarization charges, due to piezoelectric effects, are approximately confined
to a narrow region close to the interface and do not affect the potential
discontinuity. We find that the interface contribution to the valence band
offset is substantially unaffected by strain conditions, whereas the total band
line-up is highly tunable, as a function of the strain conditions. Finally, we
compare our results with those obtained for [001] heterojunctions.Comment: 18 pages, Latex-file, to appear in Phys.Rev.
GROUND FILTERING OF CO-REGISTERED MOBILE AND STATIONARY LASER SCANS BY USING SUPERPOINTS IN RANSAC PLANES
Ground filtering is an important tool for many applications. The high variability of landscapes makes it necessary to perform its computation with 3D points as the only input, that is, with as few as possible algorithm parameters and without any training data. In the case of terrestrial laser scans, an additional challenge comes from a highly inhomogeneous point density. The SiRP algorithm on ground filtering, relying on intermediate validating superpixels as ground or non-ground, was previously developed for airborne point clouds. We consider a dataset acquired by a mobile mapping system mounted on a car, which was extended by additional stationary laser scans. The registration algorithm is based on hierarchical merging. Afterwards, SiRP was applied to both uni-modal and multi-modal point clouds. Impressive qualitative and quantitative classification results with around 97 % on overall accuracy were obtained and discussed
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